The excellent and highly detailed youtube channel WWII US Bombers did a recent video on the types of contrails produced by bombers (3 kinds) and the conditions under which they were produced. The guy has apparently limitless access to Air Force archives.
No one is arguing about whether high altitude aircraft produce contrails. What is being discussed is the abrupt halting of the contrail in the video. If the video is real no one has explained that sudden, instataneous halting of the contrail.